Sprint Nextel has the third largest wireless carrier in the United States, greatly overshadowed by the Big Two: AT&T and Verizon. Their 3G network came in third behind T-Mobile's in a recent survey, and the carrier is losing millions of subscribers a year. But rather than sit and cry about it, they're taking a shot at the big dog, AT&T. In a new ad to be aired in the top wireless markets, Sprint makes fun of AT&T's often-maligned network and shows an iPhone 3G user getting 4G download speeds through Sprint's Overdrive 3G/4G Mobile Hotspot device, which is a combination WiMAX subscriber station/WiFi base station.

Wireless technology is slowly moving towards a fourth-generation (4G) system that will allow faster speeds and secure, all-IP communication from the network core to mobile devices. Several standards are evolving to implement 4G, and are in varying states of readiness. AT&T and Verizon are both moving to implement Long Term Evolution (LTE) technology, which is a step along the road to true 4G. Sprint chose to go a different route with Mobile WiMAX, a wireless Ethernet protocol based on the IEEE 802.16e-2005 standard intended to bring wireless "last-mile" connectivity similar cable modems or DSL.

Sprint is marketing the Sierra Wireless Overdrive device for use with its WiMAX network, which is currently available in 27 cities in the US, with more coming in 2010. The battery-operated portable hotspot has a 4G receiver and a WiFi base station, and allows up to five WiFi devices to connect at speeds up to 10 times faster than 3G, according to Sprint. In a new advertisement for Sprint's service, two men are shown on a park bench, with one of them ("Steve") trying to download video with an iPhone that the other character "Matt" says is "limited to AT&T's 3G speeds." After "Matt" allows "Steve" to connect to his Overdrive device, the video loads instantly.

With Apple sticking with AT&T - for now at least - as the carrier of choice for the iPhone and iPad, other carriers are trying to get a piece of the action by offering alternative data plans for the devices. Verizon's MiFi currently uses 3G, but takes advantage of Verizon's well-regarded network. The uphill battle that the competitors face is price: Verizon's best data plan costs $60 a month, and has a 5GB cap, while Sprint's WiMAX service tops out at 300MB for $59.99 a month.